code: def test_upgrade_from_6(self):
      with tempfile.TemporaryDirectory() as d:
          shutil.copytree(
              os.path.join(models_dir, "version6", "0.ckpt"),
              os.path.join(d, "0.ckpt"),
          )
          shutil.copyfile(
              os.path.join(models_dir, "version6", "0.ckpt.json"),
              os.path.join(d, "0.ckpt.json"),
          )
          ckpt = SavedCalamariModel(os.path.join(d, "0.ckpt.json"))
          self.predict_and_eval(ckpt.ckpt_path)
  
file_path: calamari/calamari_ocr/test/test_model_migration.py
imports: import os
  import shutil
  import tempfile
  import unittest
  from tensorflow import keras
  from tfaip import DeviceConfigParams
  from tfaip.device.device_config import DeviceConfig
  from calamari_ocr.ocr import SavedCalamariModel
  from calamari_ocr.ocr.predict.predictor import Predictor
  from calamari_ocr.test.test_prediction import default_predictor_params, file_dataset
label_desc: Use image node_id 3 for calling the TestModelMigration obj's underlying member method code with example usage: obj.test_upgrade_from_6() without return types